View Full Version : General Tech Timing chain replacement

10-21-2017, 07:49 PM

This may be a stupid question...

I'm going to replace the timing chain on my TR6. Is there any trick that I can use to keep the cam and crank from moving so I don't have to degree them?


Geo Hahn
10-21-2017, 08:06 PM
I have never worked on a TR6 but... should be pretty easy to immobilize the crank, then I would carefully mark the position of the cam sprocket. There should be marks already there and it would be good to take some detailed pictures of their orientation.

10-22-2017, 12:03 AM
There should be marks on the sprockets, like you may be able to barely see here. 50934 remove with the aligned in a perfectly straight line and make sure they are the same when you put them back on. You can make your own marks if you don't have them. Ideally at top dead center on piston/cylinder 1, but for purposes of maintaining cam timing only that is not absolutely required.

When I was young and didn't know any better I replaced a chain by popping a link off. and squeezing the ends of the little dowel to hold it back on, thus being careful not to turn anything and thereby not having to remove any gears. I drove the car for many years after with no problems, but would not recommend doing it that way...

10-22-2017, 09:39 AM

I understand about the marks on the sprockets, but the procedure in Bently calls to remove both sprockets and chain as an assembly. For the crank there is the key, so it's sprocket can only go on one way, so it's easy to get is lined up correctly. It's when removing/installing the cam sprocket and the cam then turning as a result that I am concerned about. I think that the cam sprocket can go on 2 ways, though I could be wrong. Is there a way to either keep the cam from turning (or is it held by the distributor), or marks on it so you can put its sprocket on the correct way?

Oh, and this is for a TR6, don't know if its different for other TR's.


P.S. My "googlefu" hasn't turned up much info on this, maybe it's obvious once I get the into it...

10-22-2017, 10:10 AM
It is a good idea to replace the 2 sprockets if you are going to put on a new chain.
You should be able to remove the cam sprocket without moving or rotating anything.
Then before removing the crank sprocket, make your own index marks on the crank and engine plate.
But in reality, I'd do the cam timing procedure and maybe advance it a few but no more than 4 degrees.

10-22-2017, 10:49 AM
Yes make the marks on the cam sprocket so you are sure it goes back on the same. Neither the crank nor the cam spin very freely in a fully assembled engine, so if you are not working on anything else it is pretty easy to keep them in place.

Replace the timing chain tensioner while you are in there, they are a cheap little strip of spring metal that pushes against the chain. They are known to wear out.